Internal combustion engine



Jan. 9, 1940. F. ZAHREN 2,186,812

INTERNAL COMBUSTION ENGINE Filed Dec. 18, 193"! 3 Shuts-Shoot 1 Amen/0r:F R A N 2 2, HREN ATTOR N EYS F. ZAI- IREN 2,186,812 INTERNALcouBus'rIon ENGINE Jan. 9, 1940.

s Sheath-Shoot 2 1 Filed Dec. 18, 1937 Oi x Jan. 9, 1940. F. ZA-HREN2,186,812

INTERNAL couausriou zuezus Fied Dec. 18. 1957 s Shoots-Shut 3 [r1vehfar' FkANZIZAHREN ATTORNEYS V Patented Jan. 9, 1940 UNITED STATESPATENT OFFICE Application December 18, weasel-in No. 180,482

6 Claims.

This invention relates to internal combustion engines, more especiallyto high-speed two-stroke internal combustion engines.

"Internal combustion engines are known provided with direct currentscavenging means and inlet slots, controlled by the working piston,distributed over the whole periphery of the cylinder and disposed in thesame zone of the cylinder. In two-stroke internal combustion engineshaving inlet slots distributed over the whole periphery of the cylinderit has been likewise proposed to .arrange the slots in tangentialdirection thereby obtaining a whirling movement resulting in a betterscavenging and mixing. However with these well-known arrangements thescavengin is incomplete, the waste gases being only partially pushed outof the cylinder. The object of the present invention is to avoid thesedrawbacks, especially to obtain,besides a satisfactory formation of themixture,fa perfect scavenging especially of the core of waste gasescontained in the middle of the cylinder.

According to the invention the side faces of each of the slots passdownwards from a tangential direction into a radial one, or inverselyfrom a radial direction into a tangential one in such a manner that whenthe inlet slots begin to be opened the entering partial currents areexclusively directed tangentially or radially, and the additionalcurrents, forming on further enlarging of the opening turn, as comparedwith the superimposed ones, more and more towards the axis or the wallof the cylinder.

, The invention will now be more fully described with reference to theannexed drawings of which Fig. 1 is a perspective view of the slotsdistributed along the periphery of the cylinder;

Figs. 2 to 4 are cross-sections through the cylinder and the slots, viz.

Fig. 2 is a cross-section through the upper part, i. e. the part of theslot which is first uncovered by the piston;

Fig. 3 shows a cross-section through about the middle part, and

Fig. 4 a cross-section through the lower part of the several slots;

Figs. 5, 5a and 5b are cross-sections through a slot showing thedifferent directions of the scavenging medium at differentcross-sections of Germany December 19, 1936 the course of the individualscave g currents,

whereas Fig. is a longitudinal section of the cylinder illustrating thecourse of the scavenging currents; 5

Figs. 11 and 12 are similar longitudinal sections showing furtheradditional modifications of the inlet slots.

The inlet slots 0, being disposed upon the cylinder wall e in uniformdistribution and in the 10 same zone of the cylinder and beingcontrolled by the piston i are shaped in such a manner that the sidefaces a and b of each of the slots 0 pass downwards from a tangential toa. radial direction.

As especially seen from Fig. 1, the tangential direction of the'upperpart 1 of the slot continuously changes into a radial or nearly radialone in the lower part g of the slot. This form of the slots is also seenin Figs. 2 to 4. When the pis- 0 ton i has first uncovered the upperpart of the side faces (land 17, the slots c pass in tangentialdirection as shown in Fig. 2.- On further movement the piston 12gradually uncovers the middle part of the slots, as about in Fig. 3which shows that in this position of the piston i the side faces a and bof each of the slots 0 do no longer pass as strictly tangential as inFig. 2. Finally, when the piston reaches the lower part g of the slots0, the side faces a' and b pass in this part radially or nearlyradially. From this formation of the slots-which of course may beinverted-it results that in the beginning of the opening of the inletslots c the entering partial currents are directed tangentially orradially as the case may be, and the additional currents formed onfurther enlargement of the opening turn towards the axis d or the wall eof the cylinder respectively. Hereby, without the single partialcurrents disturbing one another, henceforth a perfeet scavenging of thewhole cylinder is obtained, above all the detrimental core ofwaste gasesbeing surely reached, without the necessity of providing a greateramount of scavenging medium.

Fig. 5 shows the different directions of the scavenging medium atdifferent cross-sections of the opening of the slots 0 dependent uponthe position' of the piston i. The cross-section I, Fig. v 5, shows thetangential direction of the scavenging medium, the correspondinglyformed side faces a and b of the slot 0 being uncovered by the piston iat first.

Cross-section II, Fig 5a, shows the nearly radial or less tangentialcourse of the scavenging 56 medium by the formation of the side faces aand b of the slot 0 determining the course of the scavenging medium assoon as the piston 1 takes a position about in the middle of the slot 0considering its total height.

Cross-section III, Fig. 52), illustrates the radial course of thescavenging medium attained as soon as the piston i uncovers the whole ofthe slot 0.

The single currents of the scavenging medium ii, In and g1 correspondingto the cross-sections I, II and III of Figs. 5, 5a and 5b are shown inFigs. 7, 8 and 9. From these figures it is seen that the currents ofscavenging medium f1 flow tangentially (Fig. 7) the currents hl flownearly tangentially (Fig. 8), and the currents 9'1 flow radially (Fig.9).

Fig. 6 shows the same arrangement of the inlet slots 0 in perspectiveview, the single currents of scavenging medium f1, 91 and in beinglikewise indicated.

Fig. 10 representing a longitudinal cross-section of the cylinder makesclear the course of the single currents of scavenging medium resultingfrom the formation of the slots to provide such result. The singlecurrents of scavenging medium f1, hi, and g1 accomplish a perfectscavenging of the whole cylinder, the scavenging current or carryingaway the inner core of waste gases and the scavenging current hi alreadyskimming a greater area of the cylinder, whereas the scavenging current1: passes along the walls of the cylinder.

Figs. 11 and 12 show by way of example an additional modification of theinlet slots c, where the slots c-besides being formed at differentangles-are made in such a manner that the upper faces is of the slotslie at an angle nearer to the longitudinal central axis d of thecylinder than the lower faces m of the slot. Hereby I 'attainfurthermore that at the beginning of the opening of the slots 0 by thepiston i the scavenging medium does not pass or only slightly passes tothe cylinder head (see arrow A) but on further opening the slots 0 itsway is distinctly directed upwards (see arrow B) For this modificationFig. 11 shows the course of the current of scavenging medium, the upperfaces It of the slot having just been uncovered, whereas Fig. 12 showsthe course of the scavenging currents in longitudinal cross-section whenthe slots are wholly opened. The slots 0 in each case provided in acylinder may be of the same kind or of different kinds or only partly ofdifferent kinds with respect to one another whereby differentcombinations of forming the slots are rendered possible. In this case,however, it is essential to form the slots in such a manner that thesingle scavenging currents do not disturb one another so as to warrant aperfect scavenging of the waste gases out of all parts of the cylinder.

The side faces a and b of the slots .2 may also be formed in such .amanner that in contradistinction to the modification shown the distancesbetween corresponding points upon the side faces a and b are in eachcase always equal.

I claim:

1. An internal combustion engine, especially a high-speed two-strokeinternal combustion engine provided with direct current scavenging andinlet slots controlled by the working piston and distributed over theperiphery of the cylinder in the same zone, in which engine the anglebetween the side faces of each slot and the tangent to the cylindergradually varies from a value of less than 90 degrees to a total amountof about 90 degrees, and the angle between the upper faces of the slotsand the axis of the cylinder differs from the angle between the lowerfaces of the slot and the axis of the cylinder.

2. An internal combustion engine, especially a high-speed two-strokeinternal combustion engine provided with direct current scavenging, andinlet slots controlled by the working piston and distributed over theperiphery of the cylinder in the same zone, in which engine the anglebetween the side faces of each slot and the tangent to the cylindergradually varies from a value of less than 90 degrees to a total amountof about 90 degrees, the slots being diiferently formed with respect toone another.

3. An internal combustion engine, especially a high-speed two-strokeinternal combustion engine provided with direct current scavenging andinlet slots controlled by the working piston and distributed over theperiphery of the cylinder in the same zone, in which engine the anglebetween the side faces of each slot and the tangent to the cylindergradually varies from a value of less than 90 degrees to a total amountof about 90 degrees, part of the slots being differently formed withrespect to one another.

4. An internal combustion engine, especially a high-speed two-strokeinternal combustion engine provided with direct current scavenging, andinlet slots controlled by the working piston and distributed over theperiphery of the cylinder in the same zone, in which engine the anglesbetween the section lines formed in the side walls of each single slotby consecutive cross-sections perpendicular to the axis of the cylinderand the tangent to the cylinder gradually vary in the direction of theaxis from a value less than 90 degrees to about 90 degrees.

5. An internal combustion engine, especially a high-speed two-strokeinternal combustion engine provided with direct current scavenging, m

and inlet slots controlled by the working piston and distributed overthe periphery of the cylinder in the same zone, in which engine theangle between the side faces of each slot and the tangent to thecylinder gradually pass in downward direction from a radial to'atangential direction.

FRANZ ZAHREN.

